//获取当前光标位置
export default   function getCursortPosition (element) {
    var caretOffset = 0;
    var doc = element.ownerDocument || element.document;
    var win = doc.defaultView || doc.parentWindow;
    var sel;
    if (typeof win.getSelection != "undefined") {//谷歌、火狐
      sel = win.getSelection();
      if (sel.rangeCount > 0) {//选中的区域
        var range = win.getSelection().getRangeAt(0);
        var preCaretRange = range.cloneRange();//克隆一个选中区域
        preCaretRange.selectNodeContents(element);//设置选中区域的节点内容为当前节点
        preCaretRange.setEnd(range.endContainer, range.endOffset);  //重置选中区域的结束位置
        caretOffset = preCaretRange.toString().length;
      }
    } else if ((sel = doc.selection) && sel.type != "Control") {//IE
      var textRange = sel.createRange();
      var preCaretTextRange = doc.body.createTextRange();
      preCaretTextRange.moveToElementText(element);
      preCaretTextRange.setEndPoint("EndToEnd", textRange);
      caretOffset = preCaretTextRange.text.length;
    }
    return caretOffset;
  }